Reduction in thermal conductivity of Bi thin films with high-density ordered nanoscopic pores

Kim, Gil‐Sung; Lee, Mi-Ri; Lee, Seung Yong; Hyung, Jung-Hwan; Park, No‐Won; Lee, Eun Sun; Lee, Sang-Kwon

doi:10.1186/1556-276x-8-371

Cited by 11 publications

(5 citation statements)

References 26 publications

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“…Figures 1(c) and (d) show schematic of the experimental setup for the four-point-probe 3-ω measurement for measuring both the cross-plane (figure 1(c)) and in-plane (figure 1(d)) thermal conductivity. The evaluation of the thermal conductivity using 3-ω measurements has been extensively studied, including in our previous works [23,[29][30][31][32][33]. In short, the 3-ω method is normally an alternating current technique in which a thin film (Ti/Au=10/300 nm) is patterned on a SiO 2 /Si substrate (figures 1(c) and (d)) for measuring the cross-plane and in-plane thermal conductivity.…”

Section: Thermal Conductivity Measurement Using the 3-ω Methodsmentioning

confidence: 99%

Anisotropic temperature-dependent thermal conductivity by an Al₂O₃ interlayer in Al₂O₃/ZnO superlattice films

Lee¹,

Lee²,

Ahn³

et al. 2017

Nanotechnology

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The thermal conductivity of superlattice films is generally anisotropic and should be studied separately in the in-plane and cross-plane directions of the films. However, previous works have mostly focused on the cross-plane thermal conductivity because the electrons and phonons in the cross-plane direction of superlattice films may result in much stronger interface scattering than that in the in-plane direction. Nevertheless, it is highly desirable to perform systematic studies on the effect of interface formation in semiconducting superlattice films on both in-plane and cross-plane thermal conductivities. In this study, we determine both the in-plane and cross-plane thermal conductivities of AlO (AO)/ZnO superlattice films grown by atomic layer deposition (ALD) on SiO/Si substrates in the temperature range of 50-300 K by the four-point-probe 3-ω method. Our experimental results indicate that the formation of an atomic AO layer (0.82 nm) significantly contributes to the decrease of the cross-plane thermal conductivity of the AO/ZnO superlattice films compared with that of AO/ZnO thin films. The cross-plane thermal conductivity (0.26-0.63 W m K of the AO/ZnO superlattice films (with an AO layer of ∼0.82 nm thickness) is approximately ∼150%-370% less than the in-plane thermal conductivity (0.96-1.19 W m K) of the corresponding film, implying significant anisotropy. This indicates that the suppression of the cross-plane thermal conductivity is mainly attributed to the superlattice, rather than the nanograin columnar structure in the films. In addition, we theoretically analyzed strong anisotropic behavior of the in-plane and cross-plane thermal conductivities of the AO/ZnO superlattice films in terms of temperature dependence.

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Section: Thermal Conductivity Measurement Using the 3-ω Methodsmentioning

confidence: 99%

Anisotropic temperature-dependent thermal conductivity by an Al₂O₃ interlayer in Al₂O₃/ZnO superlattice films

Lee¹,

Lee²,

Ahn³

et al. 2017

Nanotechnology

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“…They have the highest resistivity and Hall coefficient of all metals and highly anisotropic Fermi surface [5][6][7][8]. A narrow fundamental band gap with a sizeable spin-orbit coupling (SOC) make 3D bismuth crystals and their surfaces crucial topologically.…”

Section: Introductionmentioning

confidence: 99%

Modification of electronic structure, magnetic structure, and topological phase of bismuthene by point defects

Kadıoğlu¹,

Kilic²,

Demirci³

et al. 2017

Phys. Rev. B

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This paper reveals how the electronic structure, magnetic structure, and topological phase of two-dimensional (2D), single-layer structures of bismuth are modified by point defects. We first showed that a free-standing, single-layer, hexagonal structure of bismuth, named h-bismuthene, exhibits nontrivial band topology. We then investigated interactions between single foreign adatoms and bismuthene structures, which comprise stability, bonding, electronic structure, and magnetic structures. Localized states in diverse locations of the band gap and resonant states in band continua of bismuthene are induced upon the adsorption of different adatoms, which modify electronic and magnetic properties. Specific adatoms result in reconstruction around the adsorption site. Single vacancies and divacancies can form readily in bismuthene structures and remain stable at high temperatures. Through rebondings, Stone-Whales-type defects are constructed by divacancies, which transform into a large hole at high temperature. Like adsorbed adatoms, vacancies induce also localized gap states, which can be eliminated through rebondings in divacancies. We also showed that not only the optical and magnetic properties, but also the topological features of pristine h-bismuthene can be modified by point defects. The modification of the topological features depends on the energies of localized states and also on the strength of coupling between point defects.

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“…In addition, studies on Bi thin films and nanowires have reported a significantly decreased thermal conductivity in contrast to its bulk value [18][19][20][21]. With good Seebeck coefficient and good electrical conductivity added with reduced thermal conductivity can make this element as a promising n-type material [22,23] and can be used in combination with good p-type thermoelectric materials for low temperature heat conversion applications [24][25][26][27][28][29].…”

Section: Resultsmentioning

confidence: 99%

Enhanced thermal sensitivity in single metal thermocouple: significance of thickness-engineering of the metal layers

Mulla¹,

Dunnill²

2021

Eng. Res. Express

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Single metal thermocouples (SMTs) have recently been developed with a new design concept of width-engineering of metal segments. In such designs, two segments of different micro-width are formed to obtain different levels of Seebeck effects. The variations in the Seebeck effect achieved from dissimilar segment width are small. In addition, the fabrication of such micro-width patterns requires special fabrication facilities such as photolithography or electron-beam lithography. In this paper, an alternative method is presented that has the potential to give high thermal sensing SMTs and requires no sophisticated facilities to fabricate. The method is based on thickness-engineering instead of widthengineering, and thus devices can be obtained from commonly available thin film deposition techniques. Constructing better thermal sensing SMTs is possible with this approach as thickness can be easily and conveniently varied down to nanoscale range which is necessary to achieve significant changes in the Seebeck effects from effectively utilizing size effects. As a result, a high thermal sensing bismuth based-SMT has been fabricated with a sensitivity of as high as 31 μV K −1 , one of the highest values reported for SMTs. It is straightforward, more convenient over width-engineering approach and thus SMTs can be easily developed.

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Reduction in thermal conductivity of Bi thin films with high-density ordered nanoscopic pores

Cited by 11 publications

References 26 publications

Anisotropic temperature-dependent thermal conductivity by an Al₂O₃ interlayer in Al₂O₃/ZnO superlattice films

Anisotropic temperature-dependent thermal conductivity by an Al₂O₃ interlayer in Al₂O₃/ZnO superlattice films

Modification of electronic structure, magnetic structure, and topological phase of bismuthene by point defects

Enhanced thermal sensitivity in single metal thermocouple: significance of thickness-engineering of the metal layers

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Reduction in thermal conductivity of Bi thin films with high-density ordered nanoscopic pores

Cited by 11 publications

References 26 publications

Anisotropic temperature-dependent thermal conductivity by an Al2O3 interlayer in Al2O3/ZnO superlattice films

Anisotropic temperature-dependent thermal conductivity by an Al2O3 interlayer in Al2O3/ZnO superlattice films

Modification of electronic structure, magnetic structure, and topological phase of bismuthene by point defects

Enhanced thermal sensitivity in single metal thermocouple: significance of thickness-engineering of the metal layers

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Anisotropic temperature-dependent thermal conductivity by an Al₂O₃ interlayer in Al₂O₃/ZnO superlattice films

Anisotropic temperature-dependent thermal conductivity by an Al₂O₃ interlayer in Al₂O₃/ZnO superlattice films